Hello PatMc,
Many thanks for the inspiration regarding laminating film for covering. I managed to find some BOSS matt 24 micron laminating film which works a dream. Very easy to apply, and no problems around corners, and shrinks very well. I got 660 feet by a foot wide for just on £30 including postage. I havn't tried painting it yet, but will try your idea of tissue and floor sealer. The Boss number for the varnish is FSM 120. Also available in gloss. I have just bought 2.5 litres of Screwfix water based varnish for £20. Hope this works OK, but decided to try it as a couple of people have been using it to varnish art products. Thanks again for the posting.
Malcolm.